Refrigerated display cases are a common feature of modern grocery stores. Typical refrigerated cases have a bottom and four lower sides defining a well, the well serving as a settling area for cool, refrigerated air, and as a display area for food products. Many modern refrigerated cases also have a tall back and top overhang with an open front to allow customers to view, inspect, and retrieve food items.
A refrigerated case having an open front requires carefully regulated air flow to maintain cool temperatures within the case. Cooled air spilling from (or room temperature air being drawn into) the case requires extra cooling. More importantly, improper air flow patterns may result in case temperatures, or temperature variations, which violate food regulations and/or result in spoiled food.
In a typical open-front case, air is pulled through a front or bottom well vent, drawn over a cooing coil within the case, pushed through a channel within the case back, and discharged either through the case back, the case top overhang, or both. Pulling air from the well bottom or front and discharging it through the case back and/or top creates a curtain of cooled air. Ideally, this air flow pattern neither discharges cool air into the room nor pulls warm room air into the case.
Competitive pressures have forced grocers to display (and sell) more goods per square foot. In response to such pressures, grocers have installed shelving units within refrigerated cases, the shelves being typically placed toward the back of the well. Such shelves create more horizontal shelf space. However, the use of such shelves may create cooling problems within the cases.
Many cases are not designed for use with shelves. Also, the food displayed on the shelves requires cool air to maintain safe temperatures. Many cases are incapable of maintaining proper temperature at the upper and middle shelves. Furthermore, the presence of the shelves themselves creates problems as upper shelves shelter lower shelves from descending cooler air and lower shelves shelter upper shelves from circulating lower air.
One approach to more evenly distributing refrigerated air over shelves positioned in a case is essentially a re-building of the cases. One re-building method in use increases the number of fans, so as to boost the total air flow up through the case back and out the top overhang. This increased air flow descending from the case overhang can increase the cooling of upper shelves. In cases where air spills in through back vents in the case, the vents have been removed by replacing the vents with solid sheet metal. By removing the back discharge vents, more air is directed to the top overhang discharge vents. Again, this directs more cooling air to upper shelves.
Adding fans to the case itself and/or blocking vents requires significant re-building of the case at considerable expense. This can require significant down time, lost sales, and often voids the manufacturer's warranty for the case. Adding fans and redirecting air through the case's air passages also has not solved the problem of poor cooling in middle shelves.